Modern wireless communications networks are typically placed under great demands to provide high data capacity within the constraints of the allocated signal frequency spectrum. In cellular wireless communications networks, capacity may be increased by re-using frequencies between cells, typically according to a predetermined frequency re-use pattern. A fixed wireless access system may comprise a base station, which may be referred to as an access point, typically mounted on an antenna tower, and a number of subscriber modules installed at customer premises. The access point may be equipped with sector antennas, each sector antenna being used to transmit and receive with a respective cell. Capacity may be further increased within a cell by steering respective beams towards specific user equipments to allow communication between the access point with improved gain and/or reduced interference reception in comparison with a sector antenna. The access point may be equipped with an antenna array and a beamformer for each sector, for forming beams for communication with each respective subscriber module.
However, it may be a regulatory requirement to detect radar transmissions in each sector, so that transmissions may be avoided if radar pulses are detected, typically by re-tuning transmissions to another frequency in so-called Dynamic Frequency Selection (DFS) systems. This may be difficult to achieve reliably if a beamformer is used on reception within a sector. Furthermore, if the beamformer is being updated iteratively, for example by perturbation, it is possible that beams may be tried in the perturbation process that may degrade reception performance so that data may potentially be lost.
It is an object of the invention to mitigate the problems of the prior art.